Steps to reproduce: Run the following code:

Box(
    modifier = Modifier.background(Color.Cyan).pointerInput(Unit) {
        detectDragGestures(
            onDragStart = {
                dragStarted = true
                Log.e("debugTag", "onDragStart")
            },
            onDragEnd = {
                dragStarted = false
                Log.e("debugTag", "onDragEnd")
            },
            onDragCancel = {
                dragStarted = false
                Log.e("debugTag", "onDragCancel")
            },
        ) { change, dragAmount ->
            change.consumeAllChanges()
            if (!dragStarted) {
                Log.e("debugTag", "onDrag called before onStart")
            } else {
                Log.e("debugTag", "onDrag")
            }
        }
    }
)

Drag anywhere in the Box.
Check the log, we can find that onDrag is always called once before onDragStart get called.

Example:

2021-05-05 11:59:43.653 19756-19756/androidx.compose.integration.demos E/debugTag: onDrag called before onStart
2021-05-05 11:59:43.653 19756-19756/androidx.compose.integration.demos E/debugTag: onDragStart
2021-05-05 11:59:43.669 19756-19756/androidx.compose.integration.demos E/debugTag: onDrag
2021-05-05 11:59:43.686 19756-19756/androidx.compose.integration.demos E/debugTag: onDrag
2021-05-05 11:59:43.703 19756-19756/androidx.compose.integration.demos E/debugTag: onDrag
2021-05-05 11:59:43.719 19756-19756/androidx.compose.integration.demos E/debugTag: onDrag
2021-05-05 11:59:43.736 19756-19756/androidx.compose.integration.demos E/debugTag: onDrag
2021-05-05 11:59:43.748 19756-19756/androidx.compose.integration.demos E/debugTag: onDrag
2021-05-05 11:59:43.749 19756-19756/androidx.compose.integration.demos E/debugTag: onDragEnd

Issue 187320697

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